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Chelation therapy still not proven to work, doctors say

Ten years ago, the National Institutes of Health launched a study to see if patients with heart disease could be helped by chelation therapy, a controversial procedure that's been used by more than 100,000

Ten years ago, the National Institutes of Health launched a study to see if patients with heart disease could be helped by chelation therapy, a controversial procedure that has been used by 110,000 Americans annually, but which many doctors regard as quackery.

One decade and $31 million later, the study's results have finally been published.

And what did authors conclude?

That they still don't know whether chelation works.

Chelation seemed to slightly reduce the risk of heart problems, mainly in people with diabetes. But that small benefit was so statistically wobbly that it could have been due to chance, according to the paper, published Tuesday in the Journal of the American Medical Association.

The study's main author said that simply running a safe trial was an achievement.

"The trial demonstrated that chelation therapy can be safely administered when rigid quality control parameters are in place, and that, under these conditions, therapy has modest benefits," said Gervasio Lamas, chairman of medicine and chief of the Columbia University Division of Cardiology at Mount Sinai Medical Center in Miami Beach, in a statement. "Safety remained paramount throughout the course of the trial."

The taxpayer-funded study, the Trial to Assess Chelation Therapy, or TACT, has been dogged by ethical and safety concerns since its onset. Chelation, which involves dripping certain chemicals into a patient's veins, is typically only used for heavy metal poisoning. In recent decades, however, doctors have claimed that it can treat everything from autism to Alzheimer's, at a cost of thousands of dollars out-of-pocket. If administered incorrectly, chelation can cause fatal complications, according to the study.

The medical journals' editors defended their decision to publish the study, but also stressed that no one should use chelation to treat heart disease.

The study "should serve to dissuade responsible practitioners from providing or recommending chelation therapy for patients with coronary disease," the journal's editors wrote in an accompanying editorial.

Critics say the study was so badly managed that its conclusions are meaningless.

"We've spent a lot of time, a lot of energy and we don't have anything to show for it," says Steven Nissen, chairman of cardiovascular medicine at the Cleveland Clinic, who was not involved in the study but wrote an accompanying editorial. "I don't think we're any closer to having evidence of a benefit than we were before this was done."

Nissen says he's concerned that practitioners of chelation will use the study to further market the procedures. "There is a real risk of harm," Nissen says.

Among the 1,708 patients heart attack survivors enrolled in the study, 26.5% of those randomly assigned to chelation later experienced a heart problem, compared with 30% of those randomly assigned to a placebo. Those heart problems included any additional heart attacks, strokes, deaths, hospitalizations for chest pain or invasive procedures to unclog arteries.

The results met the cutoff for statistical significance — the standard for judging whether a result is real or a fluke — by only 0.001.

The study is also missing crucial data, Nissen says.

Only 65% of patients received all of their scheduled chelation treatments.

And 17% of all patients dropped out of the trial, including 14% of those receiving chelation and 20% given placebo infusions. Typically, no more than about 3% of patients drop out of a study, Nissen says.

With so much missing data, doctors "can't come to any conclusions" about chelation, Nissen says.

Nissen also wonders why more patients from the placebo group dropped out of the trial, given that placebos wouldn't be expected to cause bothersome side effects. It could mean that patients knew which treatment they were getting, allowing placebo patients to drop out in order to get real chelation.

Given those uncertainties, even the authors conclude there's no medical support for using chelation to treat heart disease.

Rather than endorsing the common use of chelation, authors say their paper is "an important but single step on the long path toward better understanding" of chelation.

Chelation can bind dangerous metals, such as lead, so they can be excreted from a patient's body. The new study used a different chemical agent, which has not been approved for lead poisoning or any other use.

Doctors who practice chelation can get the chemical from compounding pharmacies, however.

Yet there are real risks. When administered too quickly, chelation can lead to a sometimes fatal drop in calcium levels in the blood.

At least 30 patients have died from unapproved uses of chelation therapy since the 1970s, including an autistic 5-year-old Pennsylvania boy, according to a 2008 report in The Medscape Journal of Medicine.

Some practitioners claim chelation can help flush calcium out of artery walls. Yet authors of the paper say they can't explain the mechanism by which chelation might really prevent heart problems.

National Institutes of Health officials have said they launched the study because there has never been any evidence that chelation therapy — which involves 120 hours of infusions administered over a year or more — is effective or safe.

"This study sheds light on a scientific controversy that has previously been untested," said Gary H. Gibbons, director of the NIH's National Heart, Lung, and Blood Institute, in a statement.

The study was temporarily halted in 2008 because of concerns over ethics and patient safety. An investigation by the federal Office for Human Research Subject Protections, which is charged with protecting patients, found that patients may not have been properly informed of chelation's risks. Several of the doctors involved in the study have been convicted of felonies.